let config = {
    connA: {
      host: 'abc123',
      user: 'abc123',
      password: 'abc123',
      database: 'abc123',
    },
    connB: {
      host: 'abc123',
      user: 'abc123',
      password: 'abc123',
      database: 'abc123',
    }
}

export interface DatabaseConnection {
  host: string
  user: string
  password: string
  database: string
}

export type DatabaseConnections<T> = {
  [P in keyof T]: T[P]
}

public static connect(config: DatabaseConnections<DatabaseConnection>) {
for (let db in config) {
  // Do something with the config
}